1. Field of the Invention
The present invention relates to a signal receiving device capable of inputting a weak voltage signal.
2. Description of the Related Art
A signal amplifier amplifying an inputted signal is in use (for example, see JP-A2007-129501 (KOKAI)). In the signal amplifier described in Document, a voltage signal inputted to a signal input terminal is converted to a current by a transistor and outputted as a current signal via a current mirror. On this occasion, if a voltage of the inputted signal is lower than a threshold voltage of the transistor, the transistor becomes in an OFF state, so that the outputted current is zero. In other words, if an inputted signal is weak, it is difficult to output a current from the signal amplifier.